R1 message periodically Based on this output, which statement is true?

Refer to the exhibits:

R1 and R2 are directly connected and IS-IS routing has been enabled between R1 and R2

R1 message periodically Based on this output, which statement is true?
A . IS-IS neighbor authentication is failing for Level 2 first and then for Level 1 PDUs
B . 1S-1S neighbor authentication is failing for Level 1 and Level 2 PDUs .
C . IS-IS neighbor authentication is failing for Level 1 PDUs only
D . IS-IS neighbor authentication is failing for Level 2 PDUs only.

View Answer

Answer: C